Fluid heating systems, such as hot water heating units, have been used to provide heat to selected spaces. Radiators, fan coils, and tubes located in floors or ceilings have been used to transfer heat from a fluid to the air in the surrounding environment. These devices require different fluid temperatures for proper operation. Fluid heating apparatus, expansion tanks, pumps, pressure balancing valves, fluid mixing devices, and air eliminators have all been separate units which have required plumbing connections usually installed on the job site. These units are typically constructed to be quite heavy to withstand fluid pressures of 100 psi or more. Proper design and installation procedures are required to avoid trapped air in pumps and other components of the heating system.
It would be advantageous to provide a fluid heating system that eliminates much of the piping and the air elimination devices, as well as the external expansion tank, fluid mixing valves, and circulator pumps required in prior art systems.
In accordance with the illustrated preferred embodiment of the present invention, a fluid heating and pumping apparatus includes a fluid tank able to withstand internal fluid pressures associated with conventional water heaters and a method of heating the fluid contained therein. Heated fluid is circulated from an outlet pipe on the fluid tank, through the environment heating circuit, and back to an inlet pipe on the fluid tank. A threaded opening is provided at the top of the fluid tank to receive a common float type air elimination valve. Contained within the fluid tank is a flexible bladder which is filled with a gas such as air or nitrogen to match the desired pressure of the fluid contained within the tank. Expansion of the heated fluid will displace the flexible bladder and compress the gas contained therein, effectively maintaining a constant fluid pressure. A pump impeller and volute housing assembly is contained within the tank. A pump motor outside the tank is connected to the impeller by a drive shaft or other drive means extending through the side of the tank. An inlet to the volute housing opens directly into the interior of the tank. An outlet of the volute housing, which is also contained within the fluid tank, is connected to the interior side of the outlet pipe. A spring operated pressure relief valve is connected directly to the outlet side of the pump volute and opens to the interior of the tank when the fluid pressure in the outlet of the pump volute overcomes the predetermined spring tension. A second embodiment of the pump assembly includes a fluid mixing housing placed over the inlet to the pump assembly with an opening connected to the interior of the tank and an opening connected to the returning fluid. A mixing apparatus proportionally mixes hot fluid from the tank with cool returning fluid in the mixing housing before it enters the pump volute and can be either manually or automatically adjusted to achieve a desired fluid temperature at the outlet pipe. This embodiment allows mounting of a number of pump and mixing apparatii around the tank to provide several different fluid temperatures from the same tank.